PIT LDVAL issue using TimerUnit_LDD on Kinetis

ScottW — Fri, 10 Feb 2012 03:07:57 GMT

I'm using a PIT timer on a Kinetis K10 to drive ADC sampling, using the TimerUnit_LDD PE component. My sampling rate is slightly off, I think because the LDVAL value is being calculated incorrectly by PE.

The datasheet (K10P81M100SF2RM Rev. 5, 8 May 2011) says on p. 985 the LDVAL register should be calculated this way:
LDVAL trigger = (period / clock period) - 1

Which in my case:
Period: 5ms (I want a 200Hz sampling rate)
Clock Period: .5us (bus running at 2MHz)

So:
LDVAL = (5000 / .5) - 1 = 9999

If I enter 5ms into the Counter Restart / Period field, the generated code for the component has this:
/* PIT_LDVAL0: TSV=0x2710 */
PIT_LDVAL0 = (uint32_t)0x2710UL;     /* Set up load register */

The hex 0x2710 is decimal 10000, (off by one from what I was expecting), and this value gives me a slight error in my sampling rate. My workaround for now is to enter a period of 4999.5us.

I'm using CW 10.1 with what should be the latest PE 10.1 patches; I also tried with CW 10.2 and I see the same behavior.

The bottom of my generated files has this for versioning:
**     This file was created by Processor Expert 5.2 [04.49]
**     for the Freescale Kinetis series of microcontrollers.

The top of the generated component file has this for versioning:
Project   : ProcessorExpert
Processor : MK10DN512ZVLK10
Component : TimerUnit_LDD
Version   : Component 01.122, Driver 01.05, CPU db: 3.00.001
Compiler : CodeWarrior ARM C Compiler

Let me know if this is a bug, or working as intended... then I'll know if I need to keep an eye on undoing this workaround if it gets modified.

Thanks!

Re: PIT LDVAL issue using TimerUnit_LDD on Kinetis

ProcessorExpert — Fri, 10 Feb 2012 22:42:03 GMT

Hello,

we will fix the PIT timing calculations according to the RM for next release of PEx.

best regards
Vojtech Filip
Processor Expert Support Team

Re: PIT LDVAL issue using TimerUnit_LDD on Kinetis

emilien — Thu, 23 Aug 2012 20:21:20 GMT

Hi,

It's seems there is the same bug for the k60:

** Project : ProcessorExpert
** Processor : MK60DN512ZVMD10
** Component : TimerUnit_LDD
** Version : Component 01.123, Driver 01.06, CPU db: 3.00.003
** Compiler : IAR ARM C Compiler

Which I could fix fast thanks to your post : )

Best regards,

Emilien

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PIT LDVAL issue using TimerUnit_LDD on Kinetis

Re: PIT LDVAL issue using TimerUnit_LDD on Kinetis

Re: PIT LDVAL issue using TimerUnit_LDD on Kinetis